Abstract

Fluorine‐doped cubic ZnS shows a photosensitive ESR center of spin ½. The signal exhibits three types of hyperfine structures; one ascribed to a fluorine nucleus, the second to four structurally equivalent Zn+ + ions, and the third to 12 structurally equivalent Zn+ + ions. The center is, therefore, assigned to an electron excess center due to F− ion incorporated substitutionally at sulfur sites. It sets forth a direct experimental evidence that in ZnS phosphors a substitutionally incorporated halide ion could trap an electron released by photoexcitation.